Posted
by
timothy
on Wednesday February 04, 2009 @04:02PM
from the as-well-they-ought dept.

An anonymous reader writes "If the US plans to develop wind farms across the country they need a better way to predict the wind direction and the duration. NCAR (National Center for Atmospheric Research) is looking to do just that. In December, NCAR signed an agreement with Xcel Energy to develop a wind prediction system for the company's wind energy farms in Colorado, Minnesota, and Texas. Experimental forecasts may start as early as May. At present, most wind forecasts rely heavily on statistical forecasting methods, since the numerical weather forecast products available from operational centers are produced with coarse-grid, larger-scale models. The RTFDDA system, however, is designed to provide a birds-eye view of local weather for small areas of special interest, like wind farms, through a multiple level downscaling algorithm." I hope that decentralized weather-data gathering stations (like many people have feeding data to The Weather Underground) would be useful for this purpose.

It's not like they turn off the windmills when there is no wind. The ones that cannot be rotated gain no benefit from knowing the direction. And the ones that can be rotated rotate automatically based on the current wind, not in anticipation of a future wind.

Perhaps I should be turning off my solar panels at night, or on cloudy days. (hmm... Actually, there are diodes to do that to prevent the panels from consuming stored energy)

What if you could tell the other electrical distributors that the wind farm would be producing a certain amount of electricity for a period of time? Perhaps the other producers wouldn't have to generate as much and cut their generation facilities back to conserve their fuel. They could purchase the "green" energy for resell to their consumers.

There are several levels of peak energy demands and a base load for an area. The base load is sort of an average over the median usages in the area. This is what is needed from the primary power suppliers. Then as peak usages approach, extra capacity has to be added to the grid. This is often done by natural gass or diesel generators and are more expensive to operate then the coal or Nuclear or other superheated steam plants. There is no capacitor or battery at the oth

Of my experience of main stream articles on research, it often completely misses the true reason behind the research. My guess is that they deemed this story more entertaining due to the interest in alternative energy. If that was the underlying reason behind the grant proposal I am sure they would not get funding for the very reason you mentioned. The data from that research seems highly valuable but for other reasons.

Why would an energy company want to have an estimate of how much or how little a particular portion of their grid is going to produce? What could they possibly do with that sort of information? It's not like our electrical grid is built to primarily rely on a very steady base load and doesn't tolerate spikes well...

There are several reasons that power generators (of any kind) want accurate weather reports.

1) Thermal generation: They have consents that limit the temperature of their waste water. If the temperature exceeds a certain temperature, they can't shed it fast enough, lowering their generation capacity.2) Wind generation: If the wind is too low, you don't generate. If it's too high, again, you don't generate. During the two points there is a curve indicating the amount of power you will generate.3) Hydro: The rain you will receive needs to be rationed over the season. No rain in the forecast, you can't generate as much power.

It's all about forecasting how much power you can generate. These providers all have contracts to provide a fixed amount of power to their customers. If they cannot meet that obligation, they have to purchase it from other providers. The sooner they know if they will have to buy on the wholesale market, the cheaper it is for them.

Otherwise, they have to be even more cautious, since the power generation from hydro and wind can be bursty. This limits their ability to supply power to those requiring guaranteed power delivery.

Actually, it is very useful to know what output your wind farm will have in the next hour or in the next day. Utilities are constantly monitoring their generation resources so they can plan ahead.
It would be beneficial to Xcel to know today that tomorrow windfarm A will not be producing as much electricity, so they can make a deal now to buy that electricity from someplace else at better prices than if they suddenly had to buy in that electricity tomorrow when they realized their windfarm wasn't producin

The economic value is in risk reduction. If we are to have a stable output of electricity, other utilities must compensate for the variability of wind power. In order to do that, they must anticipate as best as they can what the power output of a wind farm will be. If you expect that in the next 20 seconds the wind will blow less, produce more electricity with the hydraulic damn, if it will blow more, produce less, etc.

Most of the wind energy companies feel their turbine output data are proprietary. They only share it with the government if they are required to. They're worried that, if they made that data public, a competitor would use it to site another wind farm that could cause them to lose business... or could go a little upstream of the prevailing wind and cause them to lose wind flow. They don't even want to make the exact locations of their turbines public (although it's real hard to hide a whole windfarm!).

I would add that starting up windmills (getting them started) costs energy and one may want to optimize the decisions taken to start them up. E.g. if the wind forecast predicts good wind only for half an hour or so, it is probably not interesting to start it up. This is especially true for vertical windmills, which are more efficients but require more start-up work.

Also, in the long term, the forecasts may allow better location of windmill farms and their positioning.

Unless the concern is about freak high winds that exceed the capacity of the farm and pose a threat to the systems operating there, I don't see the point. Couldn't they be better served by surveying locations? Shouldn't their model be based on average output, and wouldn't historical data be a much better indicator for that? I mean it's not like there's a lot you can do to control how the wind will be blowing and the systems are hopefully already actively synced with the direction of the wind. The tie in to the grid has to be an active process anyways, in case of failure, and is produced as a byproduct of a conditioning system anyhow. Is there something I'm missing here? Is this really cheaper than sending out a guy with a weather balloon?

This doesn't seem to be a plan to better site windmills or increase their efficiency, but rather a way of predicting their near-future output to ease grid operation. If you know how much electricity your wind-farm is likely to produce tomorrow, you can better plan which non-wind power plants need to be operating, and at what levels. That can make things cheaper, because you can ramp up or down base-load power stations rather than having to rely on last-minute emergency generation when your wind farm produced less electricity than expected.

While you can get some value from a review of forecasts and observations, prior to building a wind farm, they go in, and use instruments to get measurements of the wind at various potential turbine hub heights, say, 60m, 80m, 100m, 120m, 150m. The most common instrument is a SODAR (http://www.sodar.com/about_sodar.htm) or a tall tower ("met tower") where measurements can be taken. Surveys often last up to a full year prior to data reduction and a decision on whether to use a site or not.

NCAR could be a fantastic organization, and I has already seen the info that members of NCAR had participated in IPCC stuff, published public deicing info for aviators etc..

If anything, my point seems more valid in light of those things. However the organization has chosen to position itself, and however beneficial to the public, use of the word National implies a different level of accountability.

If windmills were distributed widely enough, they could produce their own prediction data. i.e. windmill A, downwind from windmill B, should use windmill B's output as a predictor. Or, more broadly, windmill A would rely on a set of windmills within a given radius for prediction data. This would require a much larger distribution than will be available any time soon, but would probably be the best way to go in the long term. P2P wind power prediction. Me likey.

I'd also say they could create a set of historical records from sight A (22m/s @ 35 deg 10'55'') with anemometers on 1/10th of the turbines, and sight B, etc. to show wind associations with weather/climate/time of day, year/solar activity...although I'd already assume they do this, but on a far lesser scale, size and timewise.

Okay, this may be a stupid question, but I just don't know the answer:

Could the actual wind speed that we experience on the earth's surface be noticeably reduced if we go crazy building lots of wind mills? (I don't mean if you're standing right next to the wind mill tower. I'm talking about a more regional effect.)

However, the effect is debatable, with no consensus on what it will be and whether it would be negative. If we were getting to 50% wind power then I'd want to see more research on the possible effects, but I can't see it having any noticeable impact one way or the other any time soon.

Which is really why we need DIVERSIFIED energy sources. Right now, Wind is doing good on its own. Solar PV is getting funding, but that has to be the biggest mistake going. Though to be fair, in another 10 years, it probably will not be. What is needed is development work on solar thermal as well as geo-thermal power and HVAC.

If we do all that, combined with more nukes, we would be better off (lower costs of energy).

Modification to surface roughness is a consideration. Diminuation of down-stream wind velocities is a concern, and of interest, some of us are questioning how really big windfarms might qdversely affect or capability to forecast the weather as we do use surface roughness as an input into WRF. If we under-estimate surface roughness we can overestimate surface wind velocity, and see that mis-estimate propagate through the entire model. Recall, please, that th

The state of prediction in Europe isn't as good as you might think. Nor is it in corporate America. That's a big reason NCAR is getting involved. Several of us are working on how to make WRF or a similar weather model work to forecast at the appropriate heights where the turbine blades work. AND at the resolutions required.

One wind prediction company I'm aware of here claims to have resolutions as fine as 250m for the whole US. What I know of the model they're using, however, suggests that the model is